The present invention relates to an apparatus and method for forming a thin film and more particularly, to an apparatus and method for forming a thin film using an ink-jet mechanism.
Conventionally, various methods for forming a thin film have been proposed in thin film formation of an LSI semiconductor device. As one of conventionally general methods in a field of an LSI semiconductor device, there is named a CVD (Chemical Vapor Deposition) method. As another method, an SOG (Spin-On-Glass) method has also been used widely. These conventional methods are, however, not efficient, since an utilization efficiency of a film material is as low as about in the range of 5 to 20% and a majority of fed material is lost. Such a situation is specially problematic in the case where an expensive material is used as a material for forming a film. In a conventional method, a variation in thickness of a film formed is determined strictly by a pattern on a semiconductor substrate.
In a CVD method, a film thickness is dependent on a pattern density and it tends to be thinner in a higher density region. In an SOG method, a thickness of a formed film is dependent on a flow related with a viscosity of a film material and it is thinner in a broader region than in a narrower region. A control with flexibility on a semiconductor substrate is effective for executing process integration. For example, to form a thick film in a larger groove region is effective for obtaining a good planarity with a CMP (Chemical-Mechanical Polishing) method. CVD and SOG methods do not have such a controllability as can be understood from the above description. Moreover, a process tool requires that peripheral portions are free from a bead in order to protect a clamp mechanism from particle production. While, in general, the peripheral portion of a CVD film on a substrate is removed by 3 to 6 mm from the edge, this removal requires coating with photoresist, etching for removal of the film and other additional process steps including separation of the photoresist for removal of the peripheral bead, which causes a cost to be increased.
As mentioned above, in a conventional method for forming a thin film, there have been problems that utilization efficiency of a film material is low and a great amount of the material comes to be lost useless, a variation of a film thickness formed is severely determined by a pattern on a semiconductor substrate and additional process steps, which increase a cost, are necessary.